tools/testing/selftests/bpf/progs/test_tcp_check_syncookie_kern.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (c) 2018 Facebook
   3 // Copyright (c) 2019 Cloudflare
   4
   5 #include <string.h>
   6
   7 #include <linux/bpf.h>
   8 #include <linux/pkt_cls.h>
   9 #include <linux/if_ether.h>
  10 #include <linux/in.h>
  11 #include <linux/ip.h>
  12 #include <linux/ipv6.h>
  13 #include <sys/socket.h>
  14 #include <linux/tcp.h>
  15
  16 #include "bpf_helpers.h"
  17 #include "bpf_endian.h"
  18
  19 struct bpf_map_def SEC("maps") results = {
  20         .type = BPF_MAP_TYPE_ARRAY,
  21         .key_size = sizeof(__u32),
  22         .value_size = sizeof(__u64),
  23         .max_entries = 1,
  24 };
  25
  26 static __always_inline void check_syncookie(void *ctx, void *data,
  27                                             void *data_end)
  28 {
  29         struct bpf_sock_tuple tup;
  30         struct bpf_sock *sk;
  31         struct ethhdr *ethh;
  32         struct iphdr *ipv4h;
  33         struct ipv6hdr *ipv6h;
  34         struct tcphdr *tcph;
  35         int ret;
  36         __u32 key = 0;
  37         __u64 value = 1;
  38
  39         ethh = data;
  40         if (ethh + 1 > data_end)
  41                 return;
  42
  43         switch (bpf_ntohs(ethh->h_proto)) {
  44         case ETH_P_IP:
  45                 ipv4h = data + sizeof(struct ethhdr);
  46                 if (ipv4h + 1 > data_end)
  47                         return;
  48
  49                 if (ipv4h->ihl != 5)
  50                         return;
  51
  52                 tcph = data + sizeof(struct ethhdr) + sizeof(struct iphdr);
  53                 if (tcph + 1 > data_end)
  54                         return;
  55
  56                 tup.ipv4.saddr = ipv4h->saddr;
  57                 tup.ipv4.daddr = ipv4h->daddr;
  58                 tup.ipv4.sport = tcph->source;
  59                 tup.ipv4.dport = tcph->dest;
  60
  61                 sk = bpf_skc_lookup_tcp(ctx, &tup, sizeof(tup.ipv4),
  62                                         BPF_F_CURRENT_NETNS, 0);
  63                 if (!sk)
  64                         return;
  65
  66                 if (sk->state != BPF_TCP_LISTEN)
  67                         goto release;
  68
  69                 ret = bpf_tcp_check_syncookie(sk, ipv4h, sizeof(*ipv4h),
  70                                               tcph, sizeof(*tcph));
  71                 break;
  72
  73         case ETH_P_IPV6:
  74                 ipv6h = data + sizeof(struct ethhdr);
  75                 if (ipv6h + 1 > data_end)
  76                         return;
  77
  78                 if (ipv6h->nexthdr != IPPROTO_TCP)
  79                         return;
  80
  81                 tcph = data + sizeof(struct ethhdr) + sizeof(struct ipv6hdr);
  82                 if (tcph + 1 > data_end)
  83                         return;
  84
  85                 memcpy(tup.ipv6.saddr, &ipv6h->saddr, sizeof(tup.ipv6.saddr));
  86                 memcpy(tup.ipv6.daddr, &ipv6h->daddr, sizeof(tup.ipv6.daddr));
  87                 tup.ipv6.sport = tcph->source;
  88                 tup.ipv6.dport = tcph->dest;
  89
  90                 sk = bpf_skc_lookup_tcp(ctx, &tup, sizeof(tup.ipv6),
  91                                         BPF_F_CURRENT_NETNS, 0);
  92                 if (!sk)
  93                         return;
  94
  95                 if (sk->state != BPF_TCP_LISTEN)
  96                         goto release;
  97
  98                 ret = bpf_tcp_check_syncookie(sk, ipv6h, sizeof(*ipv6h),
  99                                               tcph, sizeof(*tcph));
 100                 break;
 101
 102         default:
 103                 return;
 104         }
 105
 106         if (ret == 0)
 107                 bpf_map_update_elem(&results, &key, &value, 0);
 108
 109 release:
 110         bpf_sk_release(sk);
 111 }
 112
 113 SEC("clsact/check_syncookie")
 114 int check_syncookie_clsact(struct __sk_buff *skb)
 115 {
 116         check_syncookie(skb, (void *)(long)skb->data,
 117                         (void *)(long)skb->data_end);
 118         return TC_ACT_OK;
 119 }
 120
 121 SEC("xdp/check_syncookie")
 122 int check_syncookie_xdp(struct xdp_md *ctx)
 123 {
 124         check_syncookie(ctx, (void *)(long)ctx->data,
 125                         (void *)(long)ctx->data_end);
 126         return XDP_PASS;
 127 }
 128
 129 char _license[] SEC("license") = "GPL";